Anyone who has ever seen 'This Is Spinal Tap' knows it's funny as all hell. But it takes some serious time living in the trenches of the music industry to fully understand the flip side of the coin: The rock mockumentary also does a damn fine job showcasing the undeniably frustrating and difficult side of a life dedicated to rock 'n' roll -- even if that life that has reaped the rewards of success far greater than the members of Spinal Tap ever dreamed.

"I still have a difficult time separating my anxiety from my enjoyment of this film," admitted Tool's Maynard James Keenan to Yeah! "It's equal parts flawless comedy and dangerously accurate and insightful rock documentary. Anyone who has spent any significant time on the road will most likely echo this sentiment. This film cuts to the funny bone."

Keenan is one of several dozen rockers, comedians, actors, music writers and other industry pundits to speak of their love for the comedic genius of 'Spinal Tap' -- and reveal their equally strong affinity for its ability to both document and mock-rock's dark side -- for a collection of commentaries celebrating the 30th anniversary of 'This Is Spinal Tap,' which can currently be seen for the incredibly low price of free online here (through April 11).

Some other 'Tap'-style memories from rock stars include:

"'Spinal Tap' is one of, if not the, best movies about rock music," raved Alice in Chains' Jerry Cantrell. "Both hilarious and at times a little too close to the mark for comfort."

"This movie is in my top ten," Social Distortion's Mike Ness added. "True genius. A tragic comedy! Never has a film hit so close to home. To this day, it is routinely referenced in life on the road as a musician. The unfortunate behind-the-scenes drama of the sometimes-not-so-glamorous sides of rock ‘n’ roll."

But perhaps shock rocker/movie director Rob Zombie put it best: "When I first saw 'Spinal Tap,' I was not in a band so it was nothing more to me than a very, very funny movie. Now, having been in a rock band for the last 29 years, 'Spinal Tap' is like a painfully true documentary of my life."

Our sister site Loudwire has its own set of Tap memories from rockers too. Seems like you can't be in this business without having a couple.